1. Field
The present development relates to monitoring equipment, for example, monitoring the strain on a section of underwater pipe.
2. Description of the Related Art
Gas and oil drilling is performed in many different ways, on land and at sea. In marine drilling operations, large sections of steel pipe, often referred to as “catenary risers,” are connected to stretch deep into the ocean and along the seabed. The length of this piping required to reach the sea floor, the pressure extremes, and the temperature extremes to which such pipe is subjected often result in undesirable strain and/or bends in the pipe.
The resulting bending strains the tolerances of the pipe. Unanticipated failure of such pipes can result in severe pollution and heavy economic loss. Thus, the monitoring of this “bending strain” in submerged pipes enables a continuous assessment of the integrity of the pipe.
These pipes are typically steel with several layers of insulation and anticorrosion protection to help reduce the effects of the pipe's submersion in water, particularly salt water, as well as the low temperatures and high pressures exerted at depth. The insulation and anticorrosion protection additionally help extend the longevity of the pipes, which may be in service in such harsh environments up to twenty-five or thirty years or more.
Heretofore, the strains in submerged pipes have been measured by a variety of strain sensors that are either bonded to the steel pipe surface or clamped in intimate contact with the steel surface, often using metal bands around the steel pipe. Such approaches are disruptive or damaging to the insulation and anti-corrosion coatings on such pipes. It is also time consuming and labor intensive to have to remove the layers of insulation and anti-corrosion coatings in order to attach the gauges. The clamping mechanisms themselves were typically steel or some other metal which is itself subject to the corrosive effects of the salt water—or even fresh water—in which the pipes were submerged. These approaches also can create more risk to the integrity of the pipe and/or its insulation.